Nitroguanidine Morphology in Extruded Gun Propellant
Abstract
During a study of M31A1 and M30 experimental propellants, ring patterns were discovered between the perforation holes in the outer web on the ends of grain specimens which had been prepared for impact mechanical properties measurements. No known source had ever reported this type structure. A study using both optical and scanning electron microscopy was undertaken to discover the morphological structure responsible for the rings. Results indicate that this morphology is common in extruded propellant containing nitroguanidine (NQ) crystals. The ring structure results from bands of NQ crystals that are folded in a zigzag pattern. These patterns are observed in regions that would be expected to have high flow during the extrusion process, and are caused by pin plate feed holes. NQ crystal alignment in the direction of extrusion was found in regions were large velocity gradients exist during extrusion. Dynamic mechanical properties measurements indicated that these morphological structures have little affect on the mechanical response of the propellants. Closed bomb testing, however, indicated that the burning rate of M30 was affected by the difference between the aligned and folded NQ morphology.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1987
- Accession Number
- ADA184247
Entities
People
- Robert J. Lieb
Organizations
- Ballistic Research Laboratory